Question 310517
<pre><font size = 4 color = "indigo"><b>
Let the 2nd number be x.  Then the numbers are

#1.  1
#2.  x
#3.  1+x
#4.  x+(1+x)=x+1+x=1+2x
#5.  (1+x)+(1+2x)=1+x+1+2x=2+3x
#6.  (1+2x)+(2+3x)=1+2x+2+3x=3+5x
#7.  (2+3x)+(3+5x)=2+3x+3+5x=5+8x
#8.  (3+5x)+(5+8x)=3+5x+5+8x=8+13x
#9.  (5+8x)+(8+13x)=5+8x+8+13x=13+21x  
#10. (8+13x)+(13+21x)=8+13x+13+21x=21+34x

Since term #10 is 111:

{{{21+34x=111}}}
{{{34x=90}}}
{{{x=90/34}}}
{{{x=45/17}}}

Checking, the numbers go

{{{1=17/17}}},{{{45/17}}},{{{62/17}}},{{{107/17}}},{{{169/17}}},{{{276/17}}},{{{445/17}}},{{{721/17}}},{{{1166/17}}},{{{1887/17=111}}}

Edwin</pre>